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Derek Jonesb8c038a2011-08-20 08:57:14 -0500[diff] [blame]31<td><h1>CodeIgniter User Guide Version 2.0.3</h1></td>
Derek Allard2067d1a2008-11-13 22:59:24 +0000[diff] [blame]32<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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43<a href="http://codeigniter.com/">CodeIgniter Home</a> &nbsp;&#8250;&nbsp;
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45Page Caching
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59<h1>Web Page Caching</h1>
60
61<p>CodeIgniter lets you cache your pages in order to achieve maximum performance.</p>
62
63<p>Although CodeIgniter is quite fast, the amount of dynamic information you display in your pages will correlate directly to the
64server resources, memory, and processing cycles utilized, which affect your page load speeds.
65By caching your pages, since they are saved in their fully rendered state, you can achieve performance that nears that of static web pages.</p>
66
67
68<h2>How Does Caching Work?</h2>
69
70<p>Caching can be enabled on a per-page basis, and you can set the length of time that a page should remain cached before being refreshed.
Derek Jones4b9c6292011-07-01 17:40:48 -0500[diff] [blame]71When a page is loaded for the first time, the cache file will be written to your <dfn>application/cache</dfn> folder. On subsequent page loads the cache file will be retrieved
72and sent to the requesting user's browser. If it has expired, it will be deleted and refreshed before being sent to the browser.</p>
Derek Allard2067d1a2008-11-13 22:59:24 +0000[diff] [blame]73
74<p>Note: The Benchmark tag is not cached so you can still view your page load speed when caching is enabled.</p>
75
76<h2>Enabling Caching</h2>
77
78<p>To enable caching, put the following tag in any of your controller functions:</p>
79
80<code>$this->output->cache(<var>n</var>);</code>
81
82<p>Where <var>n</var> is the number of <strong>minutes</strong> you wish the page to remain cached between refreshes.</p>
83
84<p>The above tag can go anywhere within a function. It is not affected by the order that it appears, so place it wherever it seems
85most logical to you. Once the tag is in place, your pages will begin being cached.</p>
86
87<p class="important"><strong>Warning:</strong> Because of the way CodeIgniter stores content for output, caching will only work if you are generating display for your controller with a <a href="./views.html">view</a>.</p>
88<p class="important"><strong>Note:</strong> Before the cache files can be written you must set the file permissions on your
Kenny Katzgrau283d3c82011-02-20 18:12:59 -0500[diff] [blame]89<dfn>application/cache</dfn> folder such that it is writable.</p>
Derek Allard2067d1a2008-11-13 22:59:24 +0000[diff] [blame]90
91<h2>Deleting Caches</h2>
92
Derek Jones4b9c6292011-07-01 17:40:48 -0500[diff] [blame]93<p>If you no longer wish to cache a file you can remove the caching tag and it will no longer be refreshed when it expires. Note:
94Removing the tag will not delete the cache immediately. It will have to expire normally. If you need to remove it earlier you
Derek Allard2067d1a2008-11-13 22:59:24 +0000[diff] [blame]95will need to manually delete it from your cache folder.</p>
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Derek Jones898949f2011-01-28 07:42:16 -0600[diff] [blame]111<p><a href="http://codeigniter.com">CodeIgniter</a> &nbsp;&middot;&nbsp; Copyright &#169; 2006 - 2011 &nbsp;&middot;&nbsp; <a href="http://ellislab.com/">EllisLab, Inc.</a></p>
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